The present invention relates to a method of cleaning various channels of an endoscope.
An endoscope generally has various channels for supplying or drawing by suction air or liquids. Therefore, when a used endoscope is to be cleaned, not only the outer surface thereof but also the channel interiors must be cleaned. The word "cleaning" used herein includes the steps of water cleaning for removing contaminants in the channels, disinfection with a disinfectant after such water washing, and then water washing after disinfection. These cleaning steps are usually performed in the order named above. However, in a conventional method of cleaning the channel interiors, a cleaning solution injection tube must be inserted in the port of each channel, and the valve of each channel must be opened. This requires connection of the cleaning solution injection tube into each channel and a switching operation of the valve of each channel. Procedures for cleaning channels of an endoscope have therefore been complex. With the conventional system as described above, there is an important problem in that incomplete cleaning frequently occurs, especially of the small portions of the valve body of the valve or the portion of the cylinder which is covered with the valve body.
In view of this problem, the present applicant has previously proposed, in Japanese patent application No. 56-111940, a cleaning instrument for cleaning channels of an endoscope which is free from such a problem. According to this instrument, the cleaning solution is supplied through an air/liquid supply cylinder and a suction cylinder formed in a control section of an endoscope so as to allow simultaneous cleaning of the interiors of the channels and the inner surfaces of the cylinders. More specifically, valve bodies inserted in the air/liquid supply cylinder and suction cylinder are pulled out, and adaptors are inserted in the open cylinders. Liquid supply tubes connected to these adaptors are connected to a liquid supply pump. A liquid is supplied from the liquid supply pump to the respective cylinders. The liquid is then flowed from the cylinders to the suction opening and nozzle at the distal end of the endoscope and to the air supply port, liquid supply port and suction port of the connector portion through the liquid supply channel, the air supply channel and the suction channel, respectively, thereby cleaning these channels.
However, the various channels of an endoscope generally have different inner diameters. More specifically, the air supply channel and liquid supply channel generally have small diameters while the suction channel has a large diameter. With one single channel alone, that portion of the channel which extends in the insertion section of the endoscope has a small diameter, and that portion of the channel which extends in the light guide cable has a large diameter. For this reason, when a liquid is supplied from the cylinders to the respective channels, the liquid flows to the channel or channel portion offering the least flow resistance, and a sufficient amount of cleaning solution cannot be flowed to a channel or channel portion offering a larger flow resistance. This results in a problem of incomplete cleaning of the endoscope channels.